Exploiting group communication for highly available video-on-demand services

Video on Demand services are popular today in hotels and luxury cruise boats. Increasing improvement in communication technology, will invite widespread utilization of VoD services in private homes, provided by telecommunication companies and via the Internet. In such an environment, scalability and fault tolerance will be key issues. In this paper we describe a highly available distributed Video on Demand (VoD) service, which is inherently scalable and fault tolerant. The VoD service is provided by multiple servers, that may reside in diierent sites. When a server crashes (or disconnects from its clients), it is replaced by another server in a transparent way; the clients are unaware of the change in the service provider. The VoD service exploits the Transis group communication system. Transis assists in achieving fault tolerance, and greatly simpliies the overall service design. Furthermore, the fault tolerance is achieved practically for free: it consumes negligible bandwidth, storage space, and cpu time.